Because display panel serves as a communication interface between humans and information, its development is particularly important. Among the display panels, organic electroluminescent display (OLED) has the greatest potential to become the major display product in the next generation, with the advantages including self-illuminating screen, wide viewing angle, low power consumption, simple manufacturing process, low cost, a wide operating temperature range, a high response speed and full-color display.
In addition, large-sized display billboard or display panel over 50 inch size may be mostly suspended in high space so that the viewer can view by just raising head. Therefore, if the display panel has double-side light emitting function, it will provide more information for the viewer coming or going. The current problems for double-side light emitting display panel are increasing weight and thickness and significantly raising cost.